20001001021 has 2 divisors, whose sum is σ = 20001001022. Its totient is φ = 20001001020.

The previous prime is 20001000977. The next prime is 20001001049. The reversal of 20001001021 is 12010010002.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 10681222500 + 9319778521 = 103350^2 + 96539^2 .

It is a cyclic number.

It is not a de Polignac number, because 20001001021 - 2¹³ = 20000992829 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 20001000995 and 20001001013.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20001001051) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10000500510 + 10000500511.

It is an arithmetic number, because the mean of its divisors is an integer number (10000500511).

Almost surely, 2^20001001021 is an apocalyptic number.

It is an amenable number.

20001001021 is a deficient number, since it is larger than the sum of its proper divisors (1).

20001001021 is an equidigital number, since it uses as much as digits as its factorization.

20001001021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4, while the sum is 7.

Adding to 20001001021 its reverse (12010010002), we get a palindrome (32011011023).

The spelling of 20001001021 in words is "twenty billion, one million, one thousand, twenty-one".